When dispensing a substance, such as a sealant, onto a surface of, e.g., an aircraft part or aircraft assembly in an automated manner, it is often important to control one or more properties, such as the profile or shape, of the dispensed bead.
For substances having a consistent viscosity, a desired bead shape may be achieved by controlling the flow rate of the substance, e.g., with one or more flow meters. However, flow meters may cause interference with the dispensing process and may be difficult to clean, especially when working with substances having short cure times.
For substances with variable viscosities, achieving uniform application onto a surface by controlling the flow rate may not be possible. For example, the viscosities of certain substances may change based on factors, such as temperature, pressure, compressibility, cure time, etc. Because of these factors, controlling the properties of the dispensed beads of such substances is difficult by conventional means, discussed above, which may result in either excess amounts of the substance being dispensed, thereby wasting material, and increasing weight, and/or failing to meet specification or insufficient amounts of the substance being dispensed, resulting, for example, in a seal which is out of specification. Sealed joints that are out of specification must be reworked, which substantially increases manufacturing cycle time and associated costs.